Sensor dispensing device

ABSTRACT

An embodiment of a sensor dispensing device for dispensing sensors for measuring analyte concentration in a fluid includes a cartridge assembly ( 32 ) having a housing ( 70 ) with an opening and means ( 16 ) for making a moisture-proof seal around the opening. A stack of sensors ( 12 ) is stored in the housing ( 70 ) and urged through the opening towards a stop member ( 73 ) by spring means. The device is provided with an externally actuable pusher ( 18 ) for breaking the seal and for pushing a single sensor from the housing.

[0001] This application claims priority to co-pending U.S. provisionalapplication serial No. 60/336,921 filed on Dec. 3, 2001 which isentitled “TEST DEVICE,” the disclosure of which is incorporated hereinby reference. This application also claims priority to British patentapplication serial number 0127322.6 filed Nov. 14, 2001,” the disclosureof which is also incorporated herein by reference.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to a sensor dispensing device fordispensing sensors for measuring the concentration of an analyte in afluid sample. The invention extends to a cartridge assembly containingsensors for use in the device, and to an inner member for the cartridgeassembly.

[0004] 2. Description of the Prior Art

[0005] Diabetics regularly need to test samples of their blood todetermine the level of blood glucose. The results of such tests may beused to determine levels of medication needed to treat the diabetes atthe time. In one known type of system, disposable sensors are used totest the blood. The sensors typically take the form of test strips whichare provided with a reagent material that will react with blood glucoseto produce an electrical signal. Conductive tracks on the test striprelay the electrical signal to a meter which displays the result. Aftera sample of blood has been applied to the test strip and the measurementhas been taken, the test strip is disposed of. In order to couple theconductive tracks on a test strip with the meter, the test strip needsto be inserted into a sensor holder prior to the start of testing. Thesensor holder has corresponding electrodes which are brought intoelectrical contact with the conductive tracks of the test strip. Testdevices are known in which a plurality of test strip are provided on acartridge disc. Each strip is housed in its own sensor slot, and meansare provided to eject a test strip from its slot when required, and toautomatically locate it in a sensor holder. Examples of test deviceswith test strip dispensers are described in U.S. Pat. No. 5,660,791, andEuropean Patent Application Numbers 0 732 590, 0 738 666, and 0 811 843.

[0006] A problem with test strips is that they have only a limited shelflife, and exposure of test strips to the atmosphere further reduces theshelf life.

[0007] It has been proposed in WO 94/10558 to provide a stack ofdisposable sensors in a cylindrical housing, the stack being urgedtowards a test station to form a liquid-proof seal. In DE 196 39 226 A1it is proposed to provide a test device with a cartridge that may have aplurality of chambers containing test strips, each of which chambers maybe individually sealed to preserve the shelf life of the strips therein.A user removes the seal for each chamber when required, and a timingcircuit may be activated either by the user or when the cartridge ispushed into the device. After a set time period has elapsed, an alarm orother indication reminds the user that the time period for using thestrips has elapsed.

[0008] It is an object of the present invention to provide an improvedtest device. It is a further object of the invention to provide animproved dispenser for sensors for use in measuring analyteconcentration in an applied fluid.

SUMMARY OF THE INVENTION

[0009] According to an aspect of the present invention there is provideda sensor dispensing device for dispensing sensors for testing of analyteconcentration in a fluid to be applied thereto, the device comprising:

[0010] a) a housing having a plurality of sensors arranged in a stacktherein, each sensor carrying reagent means for producing a signal inresponse to the concentration of analyte in an applied fluid;

[0011] b) the housing having an opening of sufficient dimensions topermit a sensor to pass through the opening;

[0012] c) a stop member located beyond the opening which limits outwardtravel of sensors from the stack;

[0013] d) a spring means which urges the sensors towards the stopmember;

[0014] e) a fixed gap between the stop member and the said opening ofsuitable dimensions to permit a sensor to be pushed through the saidgap;

[0015] f) a sealing member for forming a moisture-tight seal with atleast one sealing surface on or around the housing so as to protectsensors in the housing from atmospheric moisture, the relative positionsof the sealing member and the sealing surface being adjustable byexternally-actuable means to make or break the said seal; and

[0016] g) an externally-actuable pushing member for pushing a sensorfrom the said stack through the said gap to a dispensed position.

[0017] The sensor in the dispensed position may be taken by the user andused in a conventional test meter. In a preferred embodiment, however,the device further comprises signal-reading means for determining theconcentration of an analyte in an applied sample according to a signalgenerated by the sensor in the dispensed position. The signal-readingmeans may comprise electronic circuitry for measuring an electric signalgenerated by the sensor in response to analyte concentration in anapplied sample. With the sensor in the dispensed position its electrodesengage with contacts connected to the circuitry, in known manner.Alternatively, the signal-reading means may measure an optical change inthe sensor, for example a colour change. Many suitable signal-readingmeans are known to those skilled in the art.

[0018] By providing the stop member on the housing or on a supportaround the housing the sensors may be provided in a pre-assembledcartridge which can be inserted into the dispenser or into a test deviceand be ready for use without further user actions.

[0019] The stop member may be a wall of the housing so that the housingcomprises a box which is closed save for a fixed gap on one wall throughwhich the sensors are pushed, and a gap through which the pushing memberis disposed when pushing a sensor. Alternatively the stop member couldextend across only a part of the opening, sufficient to prevent sensorsfrom being urged out of the housing by the spring means. In this case,there may be a single gap which extends along one wall of the housing.

[0020] The gap could be dimensioned to permit a plurality of sensors tobe pushed simultaneously from the housing; however it is preferred thatthe gap is set such that only one sensor can pass through at a time, toprevent accidental dispensing of more than one sensor. In a preferredembodiment, the sensor adjacent to the stop member is dispensed throughthe gap.

[0021] The sealing member may comprise a cap, the cap and housing beingmovable relative to each other between an open position wherein a sensorcan pass between the cap and the housing and a closed position in whichthe cap is urged against the sealing surface, at least one of the capand the sealing surface being provided with sealing means for making amoisture-tight seal therebetween when the cap is in the closed position.The sealing means may be formed from any suitable material well known topersons skilled in the art, for example natural or synthetic rubbers,including foam rubbers. Preferred materials are thermoplasticelastomers, for example Santoprene™, a nitrile rubber mixed withpolypropylene, or thermoplastic polyurethane elastomers, for examplePellethane™. Santoprene™ elastomer is particularly preferred because itcan be processed by injection moulding.

[0022] In a preferred embodiment, the cap makes a seal with a peripheralsealing surface around the housing. However, it would also be possiblefor the cap to act as a plug and make a seal by fitting inside thehousing.

[0023] The invention provides a sensor dispensing device which can keepsensors sealed from moisture when the device is not in use and quicklydispense a single test strip for use when required.

[0024] The externally actuable means are preferably actuatedmechanically by a user moving an external actuator, for example amovable sleeve or handle on the dispenser or test device. Additionally,or alternatively, actuation may involve one or more electric or othermotorised means; for example a user may press a button which operates amotor.

[0025] The movement of the pushing member may be in the same directionas that of the external sleeve or handle, or it may be at an angle,notably perpendicular to the direction of movement of the externalactuator, by means of a series of linkages which convert translationalmotion to rotational motion and vice versa.

[0026] In a preferred embodiment, adjustment of the cap to the openposition and movement of the pushing member are actuated by adjustmentof a single external actuator. It is particularly preferred that thepushing member itself acts to adjust the cap to the open position. Thepushing member may be a slider which from an initial rest positionslides so as to insert itself between the cap and the housing, therebyadjusting the cap to the open position, and which subsequently pushes asensor from the stack to the engagement location. Preferably thearrangement is such that the pushing member undergoes reciprocalmovement.

[0027] The invention will be described with reference to the testing ofglucose concentrations in blood, but it will be understood that theinvention is not limited to this embodiment and is of generalapplicability for testing analytes in bodily and other fluids.

[0028] The sensors will typically comprise test strips of a type knownper se, and the invention will be described herein with reference to theuse of such test strips. However it will be understood that theinvention is not limited to the use of conventional test strips and thatother alternative sensors may be used.

[0029] The cartridge assembly is preferably removable, and may be soldas a separate item for refilling the test device. Accordingly, anotheraspect of the invention provides a cartridge assembly comprising:

[0030] a) a housing having a plurality of sensors arranged in a stacktherein, each sensor carrying reagent means for producing a signal inresponse to the concentration of analyte in an applied fluid;

[0031] b) the housing having an opening of sufficient dimensions topermit a sensor to pass through the opening;

[0032] c) a stop member located beyond the opening which limits outwardtravel of sensors from the stack;

[0033] d) a spring means which urges the sensors towards and intocontact with the stop member;

[0034] e) a fixed gap between the stop member and the said opening ofsuitable dimensions to permit a sensor to be pushed through the saidgap; and

[0035] f) at least one sealing surface on or around the housing formaking a moisture-tight seal with a suitable sealing member so as toprotect sensors in the housing from atmospheric moisture.

[0036] In a preferred embodiment the sealing surface is provided by asupport member in which the housing is received. In this embodiment, thehousing comprises a cartridge inner member and the support membercomprises a cartridge outer member.

[0037] The cartridge inner member may be sold and dealt in separately,so that the cartridge outer is retained and only the inner memberreplaced when necessary. Accordingly, a further aspect of the inventionprovides a cartridge inner member comprising:

[0038] a) a housing having a plurality of sensors arranged in a stacktherein, each sensor carrying reagent means for producing a signal inresponse to the concentration of analyte in an applied fluid;

[0039] b) the housing having an opening of sufficient dimensions topermit a sensor to pass through the opening;

[0040] c) a stop member located beyond the opening which limits outwardtravel of sensors from the stack;

[0041] d) a spring means which urges the sensors towards and intocontact with the stop member;

[0042] e) a fixed gap between the stop member and the said opening ofsuitable dimensions to permit a sensor to be pushed through the saidgap;

[0043] wherein the opening of the housing has two opposed long edges andtwo opposed short edges, the stop member being attached to or integrallyformed with one of the said long edges, and the said gap being laterallyaccessible through a channel disposed substantially parallel to andextending along the entire length of the other of the said long edges.

[0044] The housing may contain a desiccant to absorb moisture. In apreferred embodiment, the housing or a component thereof, for example asprung follower, may be formed from a desiccant plastics material.Suitable desiccant plastics materials are known in the art and may beobtained from CSP Technologies, Bourne End, Bucks, UK.

[0045] Any suitable spring means may be used and are well known to thoseskilled in the art. Examples are coil or compression springs, elasticmembers, or pneumatic or motorised pushing members. It is preferred thatthe spring means are constant tension springs to provide controlledmovement of the stack within the housing.

[0046] The cartridge may be removable so that the dispenser or testdevice may be re-used with a new cartridge. In another embodiment, thecartridge is loaded in the test device during manufacture and is notremovable. The device is disposed of once the sensors have all been usedor when their useful life has been exceeded. With this arrangement asingle general-purpose meter can be manufactured, the function of whichdepends on which type of sensors are in the cartridge which is loaded.

[0047] Other aspects and benefits of the invention will appear in thefollowing specification, drawings and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0048] The invention will now be further described, by way of example,with reference to the following drawings in which:

[0049]FIG. 1 shows user actions for taking a blood glucose reading usinga first embodiment of a sensor dispensing device in accordance with thepresent invention;

[0050]FIG. 2 illustrates a mechanical sequence for dispensing a sensorfrom a stack of sensors in a device in accordance with embodiments ofthe present invention;

[0051]FIG. 3 shows external views of a second embodiment of a sensordispensing device in accordance with the present invention;

[0052]FIGS. 4 and 5 show part-sectional views of the device of FIG. 3;

[0053]FIG. 6 is an exploded drawing of the device of FIG. 3;

[0054]FIG. 7 shows external views of a third embodiment of a sensordispensing device in accordance with the present invention;

[0055]FIGS. 8 and 9 show part-sectional views of the device of FIG. 7;

[0056]FIG. 10 is an exploded drawing of the device of FIG. 3;

[0057]FIGS. 11 and 12 are part-sectional views of a fourth embodiment ofa sensor dispensing device in accordance with the present invention;

[0058]FIG. 13 is an exploded view of a cartridge assembly for use in asensor dispensing device according to the invention;

[0059]FIG. 14 shows steps in the manufacture of an alternativeembodiment of a replacement cartridge assembly for use in a sensordispensing device according to the invention;

[0060]FIGS. 15 and 16 show details of the sealing arrangement of anembodiment of a sensor dispensing device in accordance with theinvention;

[0061]FIG. 17 is an exploded view of a preferred contact assembly for asensor dispensing device in accordance with the invention; and

[0062]FIG. 18 is a sectional view of a preferred sealing arrangement ofa device in accordance with the invention.

DETAILED DESCRIPTION

[0063] In the following description the same numbers will be used torefer to equivalent parts of the various embodiments.

[0064] Referring to FIG. 1, the sensor dispensing device 2 can be heldin a user's hand. The device 2 has an external slidable sleeve 4 and adisplay 6, in this example an LCD. From the rest position of FIG. 1a,the user pulls back the actuating sleeve 4 (FIG. 1b) against a springforce. As will be explained later, this action opens the cap on a stackof sensors in a housing. The user releases the sleeve 4 (FIG. 1c) andthe spring force returns the sleeve 4 to the rest position, in theprocess of which the device is activated to take a reading, a sensor 8,in this example a test strip, is presented to receive a drop of blood,and the cap returns to make a seal with the housing. The user applies asample of blood to the sensor 8 (FIG. 1d) and the glucose value is shownon the LCD 6. The used sensor 8 is then discarded.

[0065]FIG. 2 illustrates schematically the mechanical sequence of eventsoccurring inside the device 2. A cartridge assembly 32 comprises acartridge outer 10 which encloses a cartridge inner 70. The cartridgeinner 70 is a housing which has a single opening covered by aspring-biased cap 16. In the rest position shown in FIG. 2a, the cap 16is pressed against the cartridge outer 10 to make a moisture-tight seal.In the housing 70 is a stack 12 of test strips 8, urged towards the cap16 by a sprung follower 14. A stop member (best illustrated in FIGS. 13and 14) limits outward travel of the test strips 8 towards the cap 16,and the stack 12 bears against the stop member. A slider 18 outside thecartridge assembly 32 is operatively connected to the sleeve 4. As theuser pulls the sleeve 4 back, the slider 18 is pulled backwards. As theslider 18 moves backwards (FIG. 2b) a leading edge of the slider 18 isinserted between the cartridge outer 10 and the cap 16, initiallyforcing the cap 16 upwards and then forcing the stack 12 down slightlyagainst the spring force. When the slider 18 has passed fully over thestack 12 (FIG. 2c), the sprung follower 14 urges the top test strip 8 upinto the return path of the slider 18. As the slider 18 is returned backto the rest position it moves the top test strip 8 to an engagementlocation at which its electrodes engage with contacts of the testdevice. At this point (FIG. 2d) the slider 18 has removed itself frombetween the cartridge outer 10 and the cap 16 so that the cap 16 onceagain seals against the cartridge outer 10. The test strip 8 is readyfor use.

[0066] Referring now to FIGS. 3 to 6, a second embodiment of theinvention is described. The actuating sleeve 4 is mounted either side ofthe upper 22 and lower 46 meter casings. The sleeve 4 accommodates leftand right handed users and allows various gripping strategies. The metercasing 22, in this example formed from an acrylic material, is providedwith a front-mounted LCD 6, key-pad function buttons 20, and stripejection slot 24. The LCD key-pad, and other meter electronicscomponents are mounted on a main PCB 42 which is in turn connected to asecond PCB 30. The second PCB 30 is electrically connected to a contactblock 28, with which the electrodes of the test strip 8 engage when thestrip is in the engagement location, as best shown in FIG. 17.

[0067] Cartridge access from the side of the device is provided by acartridge cover 44 which is opened by operation of a release button 26.In this example the cartridge cover 44 provides access to batteries 38in addition to the cartridge assembly 32. The batteries 38 and cartridgeassembly 32 are received in a single moulded chassis 50. A downloadsocket 40 is provided for downloading external data such as calibrationvalues for the test strips. The sleeve 4 is connected to an actuatorrack 36 which is connected to a strip-pusher rack 34 via a pinion geararrangement (not shown in FIGS. 3-6—illustrated in FIG. 9). When theuser pulls back the sleeve 4, the actuator rack 36 causes thestrip-pusher rack 34 to move a greater distance because of the piniongear-ratio. The strip-pusher rack 34 is connected to the slider 18 whichoperates as described with reference to FIG. 2 above. A return spring 48acts to return the sleeve 4 to the rest position after it has beenpulled back and released.

[0068] A third embodiment of the invention is illustrated with referenceto FIGS. 7 to 10. In this embodiment the LCD 6 is side-mounted tomaximise the gripping area without obscuring the screen. Thisarrangement facilitates holding the device with a precision pen-stylegrip as well as in a fist. The strip ejection point 24 is situated at anedge projection, which helps to indicate to the user where the stripwill emerge from. A separate battery cover 54 is provided, which has abattery contact member 52 provided on its inner surface. As illustratedin FIG. 9, the actuator rack 36 engages with the smaller wheel of apinion gear 56, while the strip-pusher rack 34 is driven by the largerwheel of the pinion gear.

[0069] A fourth embodiment of the device is shown in FIGS. 11 and 12,which employs an alternative mechanism for driving the slider 18. Here,the sleeve (not shown) is directly connected to an actuating plate 60which has an arcuate slot 62 therein. The slider 18 is provided with aprojection that sits in a slot at one end of a pivot arm 58. Thearrangement is such that turning of the pivot arm 58 produces lineartranslation of the slider 58 by virtue of lost motion in the slot. Thepivot arm 58 is provided with a projection or pin 64 which is disposedin the arcuate slot 62 so that sliding of the actuating plate 60 causespivoting of the pivot arm 58 and hence sliding of the slider 18.Referring to FIG. 12, it will be seen that sliding the actuating plate60 from the upper position (shown in white) to the lower position(shaded) causes the slider 18 to move from the rest position shown onthe extreme right, to the position shown on the extreme left. Reversalof this movement, for example by means of a spring, dispenses the teststrip 8 as previously described.

[0070] One way of manufacturing the cartridge assembly 32 is illustratedin the exploded diagram shown in FIG. 13. The assembly comprises acartridge outer 10 which has a single opening. A resilient seal 66, forexample of a thermoplastic elastomer, is provided around the opening.Within the cartridge outer 10 is a cartridge inner 70 which houses aconstant tension spring 68 operatively connected to a follower 14. Thecartridge inner 70 is formed from a base member 71 and a closure member72. Two opposed upstanding walls of the base member 71 are provided witha series of ridges 74 in which fit arms 76 of the follower 14. Theridges 74 and arms 76 are profiled to permit movement of the follower 14in one direction only, towards the stack 12 of test strips. Duringassembly, the follower 14 is located near to the spring 68 to permit thestack 12 to fit in the cartridge inner 70. The closure member 72 issnap-fitted on the base member 71 to form the cartridge inner 70 whichis located in the cartridge outer 10. A lip 73 on the closure member 72provides a stop member which limits outward travel of the stack 12.There is a sufficient gap between the lip 73 and the adjacent walls ofthe base member 71 (which define an opening of the housing) to permit asingle strip 8 to slide out axially, as illustrated with reference toFIG. 2.

[0071] An alternative cartridge assembly design, for a replacementcartridge assembly 32, is shown in FIG. 14. Here the stop member 73 isprovided on the base member 71. After closing the closure member 72(FIG. 14a) the cartridge inner 70 is put in the cartridge outer 10 (FIG.14b) to form the cartridge assembly 32. An elongate channel 75 isdisposed parallel to the top edge of the closure member 72, allowingaccess of a pushing member, from the side or the top as viewed, to pushout the test strip adjacent to the stop member 73. Finally the cartridgeassembly 32 is put in a foil bag 82 (FIG. 14c) and sealed. The bag maybe provided with a desiccant to keep the cartridge assembly 32 in a lowmoisture environment.

[0072] It is preferred that the cartridge assembly 32 comprise both thecartridge inner 70 and the cartridge outer 10, so that both theseelements are replaced together. This arrangement ensures that theresilient seal 66 is periodically replaced. However, it will beappreciated that the cartridge inner 70 could be separately replaced andthe cartridge outer 10 could be re-used.

[0073] Referring now to FIGS. 15 and 16, these illustrate a preferredembodiment in which the cap 16 is provided with a profiled wall 78 thatfits into and engages with the resilient seal 66 to form amoisture-tight seal when the cap is in the closed position.

[0074] In the sealing arrangement shown in FIG. 18, the cap 16 ispivotally mounted on a fixed pivot 98 and urged into sealing engagementwith the resilient seal 66 by a spring 94. The arrangement is such thatthe spring force is exerted at a central point 96 on the cap 16, therebyhelping to spread the spring force evenly around the entire periphery ofthe seal 66 to facilitate complete closure of the cap 16 and sealing ofthe cartridge inner 70 from atmospheric moisture.

[0075] In a preferred embodiment, the sensor dispensing device has aninsert moulded contact block 28 to reduce tolerance issues and assemblycosts. A preferred construction of the contact block 28 is illustratedin FIG. 17. The contact block 28 is formed from a first 86 and a second88 moulded member which fit together. Each moulded member is providedwith a location pin 84 to engage in recesses in the chassis throughholes 92 in the PCB 30. Contacts 90 in the second moulded member engagewith electrodes on the test strip 8 and are electrically connected withthe main PCB 42 via a flexible connector 80.

[0076] Although the invention has been described with reference to asensor dispensing device or test device for measuring blood glucoseconcentration, it is to be understood that the invention is not limitedto this application. The invention may be used in the determination ofany analyte in a fluid, biological or otherwise, by the use of suitablereagents in the test strip. Such reagents are well known to thoseskilled in the art.

[0077] It is appreciated that certain features of the invention, whichare for clarity described in the context of separate embodiments, mayalso be provided in combination in a single embodiment. Conversely,various features of the invention which are, for the sake of brevity,described in the context of a single embodiment, may also be providedseparately or in any suitable subcombination.

[0078] While the present invention has been described with reference tospecific embodiments, it should be understood that modifications andvariations of the invention may be constructed without departing fromthe spirit and scope of the invention set forth in the following claims.

What is claimed is:
 1. A sensor dispensing device for dispensing sensorsfor testing of analyte concentration in a fluid, the device comprising:a) a housing having a plurality of sensors arranged in a stack therein,each sensor carrying reagent means for producing a signal in response tothe concentration of analyte in an applied fluid; b) the housing havingan opening of sufficient dimensions to permit a sensor to pass throughthe opening; c) a stop member located beyond the opening which limitsoutward travel of sensors from the stack; d) a spring means which urgesthe sensors towards the stop member; e) a fixed gap between the stopmember and the said opening of suitable dimensions to permit a sensor tobe pushed through the said gap; f) a sealing member for forming amoisture-tight seal with at least one sealing surface on or around thehousing so as to protect sensors in the housing from atmosphericmoisture, the relative positions of the sealing member and the sealingsurface being adjustable by externally-actuable means to make or breakthe said seal; and g) an externally-actuable pushing member for pushinga sensor from the said stack through the said gap to a dispensedposition.
 2. A sensor dispensing device as claimed in claim 1, furthercomprising signal-reading means for determining the concentration of ananalyte in an applied sample according to a signal generated by the saidsensor at the said dispensed position.
 3. A sensor dispensing device asclaimed in claim 1, wherein the pushing member and the means for makingor breaking the seal are actuated by operation of a single externalactuating member.
 4. A sensor dispensing device as claimed claim 3,wherein the actuating member is slidably mounted in relation to thehousing.
 5. A sensor dispensing device as claimed in claim 1, whereinthe pushing member is reciprocally slidable between a first position anda second position.
 6. A sensor dispensing device as claimed in claim 5,wherein the arrangement is such that movement of the pushing member fromthe first position to the second position will cause the pushing memberto insert at least a portion of itself between a sealing surface and thesealing member so as to break the seal and then to travel to an extentsufficient to permit a sensor to be urged to a position where it will bepushed through the gap by the pushing member in the course of its returnjourney to the first position.
 7. A sensor dispensing device as claimedin claim 6, wherein the arrangement is such that the pushing member willpush in opposite directions on both the sealing member and the nearestsensor in the stack as it travels from the first position to the secondposition.
 8. A sensor dispensing device as claimed in claim 5, whereinthe pushing member is urged from one position to the other by springmeans.
 9. A sensor dispensing device as claimed in claim 8, wherein thepushing member is urged to the first position by spring means.
 10. Asensor dispensing device as claimed in claim 3, wherein the pushingmember is connected to the actuating member by means of a rack andpinion gear arrangement.
 11. A sensor dispensing device as claimed inclaim 3, wherein the actuating member is connected to the pushing memberby means of linkages which convert a first translational motion torotational motion and then convert the rotational motion to a secondtranslational motion.
 12. A sensor dispensing device as claimed in claim11, wherein the direction of the second translational motion issubstantially perpendicular to the direction of the first translationalmotion.
 13. A sensor dispensing device as claimed in claim 1, whereinthe sensors comprise amperometric biosensors having electrode tracksthereon for outputting an electrical signal in response to theconcentration of analyte in a fluid when applied thereto, and whereinthe device further comprises electrical contacts mounted in relation tothe housing for engaging with the said electrode tracks at the saiddispensed position; and wherein the said signal-reading means comprisesa meter connected to the electrical contacts, having electronics meansfor producing a signal output which is dependent on the electricalsignal from a sensor when the sensor is engaged with the said contacts.14. A sensor dispensing device as claimed in claim 1, wherein thehousing is part of a removable cartridge assembly.
 15. A cartridgeassembly for use in a sensor dispensing device in accordance with claim14, the cartridge assembly comprising: a) a housing having a pluralityof sensors arranged in a stack therein, each sensor carrying reagentmeans for producing a signal in response to the concentration of analytein an applied fluid; b) the housing having an opening of sufficientdimensions to permit a sensor to pass through the opening; c) a stopmember located beyond the opening which limits outward travel of sensorsfrom the stack; d) a spring means which urges the sensors towards andinto contact with the stop member; e) a fixed gap between the stopmember and the said opening of suitable dimensions to permit a sensor tobe pushed through the said gap; and f) at least one sealing surface onor around the housing for making a moisture-tight seal with a suitablesealing member so as to protect sensors in the housing from atmosphericmoisture.
 16. A cartridge assembly as claimed in claim 15, wherein thehousing comprises a cartridge inner member, and wherein the cartridgeassembly further comprises a cartridge outer member in which thecartridge inner member is located, the sealing surface being providedaround the periphery of the cartridge outer member.
 17. A cartridgeassembly as claimed in claim 16, wherein the said sealing surface isprovided on a flange around the cartridge outer member.
 18. A cartridgeassembly as claimed in any claim 15, wherein the opening of the housinghas two opposed edges, the stop member being attached to or integrallyformed with one of the said opposed edges and spaced apart from at leasta portion of the other opposed edge.
 19. A cartridge inner member for acartridge assembly in accordance with claim 18, the cartridge innermember comprising: a) a housing having a plurality of sensors arrangedin a stack therein, each sensor carrying reagent means for producing asignal in response to the concentration of analyte in an applied fluid;b) the housing having an opening of sufficient dimensions to permit asensor to pass through the opening; c) a stop member located beyond theopening which limits outward travel of sensors from the stack; d) aspring means which urges the sensors towards and into contact with thestop member; e) a fixed gap between the stop member and the said openingof suitable dimensions to permit a sensor to be pushed through the saidgap; wherein the opening of the housing has two opposed edges, the stopmember being attached to or integrally formed with one of the saidopposed edges, and spaced apart from at least a portion of the otheropposed edge.
 20. A cartridge assembly as claimed in claim 15, whereinthe dimensions of the gap are such as to permit only a single sensor ata time to be pushed through the gap.
 21. A cartridge assembly comprisinga housing having opposed first and second walls, a plurality of testmembers arranged in a stack therein, each test member carrying reagentmeans for producing a signal in response to the concentration of analytein an applied fluid, a spring means which urges the stack towards andinto contact with the second wall, the housing having a gap adjacent tothe second wall of suitable dimensions to permit a test member to bepushed through the said gap; wherein at least one sealing surface isprovided on or around the housing for making a moisture-tight seal witha suitable sealing member so as to protect test members in the housingfrom atmospheric moisture.
 22. A cartridge assembly as claimed in claim21, further including a support member in which the housing is receivedand on which the said sealing surface is provided.
 23. A cartridgeassembly as claimed in claim 20, wherein the dimensions of the gap aresuch as to permit only a single test member at a time to be pushedthrough the gap.
 24. A test device for testing of analyte concentrationin a fluid to be applied thereto, the device comprising: a) a pluralityof test members arranged in a stack, each test member carrying reagentmeans for producing an electrical signal in response to theconcentration of analyte in an applied fluid and having a plurality ofelectrode tracks for transmitting said electrical signal; b) a cartridgeassembly comprising a housing containing the said stack of test members,the housing having an opening and a peripheral sealing surface aroundthe opening, and a stop member above the opening which limits outwardtravel of test members from the stack, the said stack of test membersbeing urged towards the stop member by spring means; wherein there is agap between the stop member and the opening of suitable dimensions topermit a single test member to be pushed from the housing through thesaid gap; c) electrical contacts mounted in relation to the housing forengaging with electrode tracks on a test member at an engagementlocation; d) a meter connected to the said electrical contacts, havingelectronics means for producing a signal output which is dependent onthe electrical signal from a test member when the test member is engagedwith the said contacts; e) a cap for closing the said opening, the capand housing being movable relative to each other between an openposition wherein a test member can pass between them and a closedposition in which the cap is urged against the sealing surface, at leastone of the cap and the sealing surface being provided with sealing meansfor making a moisture-tight seal therebetween when in the closedposition; f) an externally actuable pushing member which is reciprocallyslidable between a first position and a second position, the arrangementbeing such that movement of the pushing member from the first positionto the second position will cause at least a part of the pushing memberto be inserted between the sealing surface and the cap so as to adjustthe cap to the open position and to push the stack of test membersagainst the force of the spring means, and then to travel to an extentsufficient to permit a test member to be urged to a position where itwill be pushed through the said gap to the engagement location by thepushing member in the course of its return journey to the firstposition.